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1 Background and Functional Requirements for High‐Density Communications

This introductory chapter covers two topics: (i) a basic introduction to the underlying technologies and principles that apply to High‐Density Communications (HDC), but not high‐density specifics, which are covered in the chapters that follow, and (ii) a discussion of the main requirements for HDC in the context of key use cases. Use cases include airports, stadiums, convention centers, classrooms, amusement parks, train and subway stations, large multiple dwelling units, open air special events, and other venues.¹

As the second decade of the twenty‐first century rolled along, however, a new requirement presented itself due to the worldwide pandemic: physical/desk distancing in support of Office Social² Distancing (OSD) and Office Dynamic Cluster Monitoring and Analysis (ODCMA). A “de‐densification” effort was established at the time. The de‐densification effort in the workplace impacts a large number of factors, including network connectivity services and architectures. Propitiously, wireless technologies have been harvested to address and manage these pressing distancing issues. Even if effective vaccines are found and distributed globally, many agree that some of the societal and workplace changes driven by the pandemic may become permanent. One change likely to remain is the increased reliance on Work From Home (WFH) and along with it, are the implications of greater utilization of a global workforce in what might be called Outsourcing 2.0 (with the 1.0 version having taken place in the 1990s and 2000s). However, “the sun will rise again,” and in a few years, people‐based HDC may yet again become the norm; in the meantime, a large population of Internet of Things (IoT) devices may indeed require HDC support, and during the pandemic, the e‐commerce warehouse use case continues to need HDC support. Thus, while “social distancing” was a short‐term goal at press time, the business‐ and public‐venue high‐density requirements are expected to resurge and/or continue over time. Further discussion of these issues is provided in the latter part of the chapter.

1.1 BACKGROUND

The principal ways people currently communicate (especially when away from home) are via 4G/Long‐Term Evolution (LTE) cellular access, for both voice and data, and/or via a public, institutional, or corporate Wi‐Fi™ hotspot. In less populated areas and while in motion, cellular access is typically the norm, rather than Wi‐Fi access. In large business and commercial buildings (e.g. skyscrapers, hospitals, hotels), internal systems known as Distributed Antenna Systems (DASs) may be used to provide better signal quality to cellular users; these systems interoperate with the public cellular network in a number of ways. When stationary, both choices may be available.

      Cellular services are offered by carriers using specific carrier‐allocated Radio Frequency (RF) spectrum. Relatively high monthly fees are incurred; additionally, there may be both physical and administrative limits to the amount of bandwidth and interval‐accumulated throughput. Wi‐Fi makes use of bands that are freely allocated; services could be free or could be nearly free based on some account subscription arrangement.

      There are plusses and minuses with both technologies: a signal associated with a cellular service such as 4G/LTE reaches longer distances and is often the best choice in sparsely populated areas (assuming the service is available); high‐speed mobility is supported and roaming between towers (cellular access points) is seamless; the service is typically provided by well‐established carriers that have experience with availability and Quality of Service (QoS) metrics; large portions of the United States are covered, and; the session bandwidth is often guaranteed for the session's duration once the session is established. Conversely, the service costs for 4G/LTE are relatively high and there are limits to the user throughput; there is relatively limited practical competition among carriers; large base‐station antennas are needed to cover large geographic areas; the technology is complex; indoor reception of voice and data can be problematic, creating the need for more indoor antennas; and 5G will require smaller (therefore, a larger number of) cells. Wi‐Fi is often perceived to be free; the technology is simpler; the hardware and infrastructure are cheaper; it is a consistent technology between the office and the home; there is more competition in the sense that various establishments (e.g. stores, coffee shops, malls, libraries, institutions) make Wi‐Fi service available. However, the technology is subject to interference; the distance is limited; roaming does not work across different providers and may not even work for

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